1. Field of the Invention
This invention relates to a smoke curtain of the type used in ceiling assemblies.
2. Description of Related Art
A smoke curtain is a device intended, in the event of a fire, to prevent smoke from rising rapidly in offices, escalators, atriums, or other open areas, and spreading throughout a multi-story building. In so doing, a smoke curtain increases the time for evacuation of people and equipment from floors above the level of the fire. An additional, more day-to-day advantage of certain smoke curtains is that they help lessen ceiling clutter.
In one type of smoke curtain arrangement used in ceiling assemblies, a sheet of glass or transparent plastic, which forms a smoke shield, is permanently installed in such a way that it extends downward perpendicular to the plane of the ceiling. With this type of prior art smoke curtain installation is quite time-consuming since the large individual glass sheets are very heavy, must be handled very carefully to avoid breakage. The sheets must then be bolted or screwed onto a ceiling fixture at several points along their length. The worker(s) normally must do so while standing on a ladder or platform. Also, if any of the installed sheets breaks, an entire section of the ceiling must normally be replaced in order to remove and replace the broken sheet. All of the above time-consuming installation difficulties create unnecessary expense and time. As with the installation problems, there is an attendant high cost of repair.
In another type of smoke curtain arrangement, a drywall soffit is used instead of a glass sheet to form the smoke shield which protrudes from the ceiling. Like the glass sheet, however, the drywall soffit is difficult to replace. In addition, dryuwall has even less structural integrity than glass. An additional disadvantage of the drywall soffit is that it is difficult to miter smoothly two sections of drywall where they must meet at an angle. Accordingly, the drywall is often aesthetically unappealing as compared to the interior designs of many modern commercial buildings.
Because of the difficulty of replacing known smoke curtains which use glass sheets and drywall soffits as smoke shields, it is normally unwise to use these shields themselves to support other ceiling components.
In addition to the poor accessibility of existing smoke curtains of glass and drywall, a further disadvantage of these known smoke curtains is that it is difficult or impossible to integrate them and their supporting structures into other ceiling assemblies such as ventilation air bars and sprinklers. This makes them particularly disadvantageous when it is necessary for the smoke curtain to round a corner.